Polycarbonates are well-known commercially available resinous materials having a variety of applications. They are typically prepared by the reaction of dihydroxy compounds with a carbonate precursor, such as phosgene, in the presence of a catalyst. Methods of direct phosgenation, interfacial condensation and transesterification, for the preparation of polycarbonates, are described in detail in "The Chemistry and Physics of Polycarbonates", by H. Schnell, John Wiley and Co., N.Y., 1964.
Polycarbonates are high temperature, high performance engineering thermoplastics having a combination of good thermal and mechanical properties, especially when prepared from one or more aromatic diols. The blending with polycarbonates of additional compounds, such as for example, other thermoplastic resins, copolymer rubber compounds, and the like, is commonly practiced in order to improve one or more properties of the homopolymer polycarbonate.
A blend of polycarbonate, polyester, and a third impact modifying component is known. U.S. Pat. Nos. 4,257,937 and 4,677,148 disclose the use of acrylate and other rubber-containing impact modifiers in blends of polycarbonate and polyester. U.S. Pat. Nos. 4,180,494 and 4,654,400 disclose the incorporation of acrylate or butadiene based core-shell copolymers as impact modifiers for polycarbonate/polyester blends. These references do not, however, suggest the incorporation of a polyalkyleneoxide rubber.
U.S. Pat. No. 4,221,889 discloses a copolymer of a divinyl polyester and a polymerizable monomer, such as styrene, additionally containing as a toughener a polyepihalohydrin or copolymer of epihalohydrin and a monomer having an epoxide group. During polymerization of the epihalohydrin, the epoxide group opens, forming a polymer chain containing ether oxygen atoms in its backbone. The reference does not teach the toughening of a homopolymer polyester by the addition of polyepihalohydrin. It likewise does not suggest that the polyepihalohydrin might eliminate the usual requirement of drying the blend prior to extrusion, since the resinous blends disclosed in the reference are liquid when molded.
U.S. Pat. No. 4,444,940 discloses a blend of a polycarbonate, a rubber modified copolymer such as an ABS rubber, and a third component copolymer comprising an unsaturated epoxide-containing monomer and an olefin. The third component is polymerized through the double bonds on both the epoxide-containing monomer and the olefin, thereby resulting in a polymer chain having pendant epoxide groups and no ether linkages in its backbone.
Finally, U.S. Pat. No. 4,554,315 discloses a blend of a polycarbonate, a polyester, a graft copolymer, and a polymeric modifier prepared from an olefinically unsaturated monomer having at least one epoxide group. This polymeric modifier likewise polymerizes through the olefinic unsaturated site, resulting in a polymer chain having pendant epoxide groups and no ether linkages in its backbone.